This invention relates to the design area of cartridges used in typewriters or impact printers, for all applications.
It is estimated that there are fifteen to twenty million computer printers in the hands of personal and business users as of Aug., 1989, with five million additional units being sold each year. This new cartridge design will fit forty models presently on the market, produced by eight manufacturers, exceeding twelve million units.
Typical computer printers (the primary market), have an enclosed plastic ribbon cartridge with the ribbon usually made of Nylon, of 3 to 5 mills thickness, which is inked initially at the factory to a saturation level of 17% to 18% percent. Said looped ribbons are usually between twenty five and forty two point five feet in length, and produce acceptably dark print when new, but gradually fade out during their practical life span, which does not exceed eighty to one hundred single-spaced pages. This means that lengthy documents will be unacceptable in print density, since the printout is progressively lighter with each succeeding page, which a flip-through of the pages dramatically demonstrates.
Several design attempts have been made to solve this gradual fade-out problem, with mixed results. Notable is the external re-inker device which requires the removal of the cartridge from the printer, letting it run on this device for a period of thirty minutes, to achieve a reasonably uniform distribution of ink, with the user having to wear gloves to keep the ink off their hands and clothing.
Other units have the re-inker built into the cartridge by employing a square or rectangular felt or open-celled foam rubber pad, with a short wick to draw the ink, by capillary action, from the pad onto a roller, that in turn transfers it onto the passing ribbon. However, this pad arrangement must be inked to near saturation before the capillary action functions, and the particulant in the ink (coloring agent) causes the cells of the rubber, or the passageways of the felt, to partially or completely clog. Thus--capillary action, alone, is insufficient to do the job. Also, when this pad is inked, the ink, over time, will settle down to and out of the bottom of the pad, eventually causing the cartridge to leak ink through the drive-gear hole or the opening in which the passive gear yoke resides.
This new design, market tested for ten months, overcomes the above described problems with a short, continuous, Mobius looped ribbon, consisting of a 180 degree twist before it is seamed together. This invention provides solutions to the above problems by having one or more built in re-inking rollers, with a re-inking access hole(s) axially centered over these re-inking rollers so that the user can re-ink or add a shot of lighter fluid to the cartridge symmetrically, at the roller's center, whenever ink or lighter fluid is needed, without the design permitting an build-up at the spot where the ribbon rests against the rollers when the printer is not in use. This last, important feature, made practical by a tension spring of a precise compresion value, will be described further in this document.